U.S. Pat. No. 3,922,529 discloses an apparatus for reading data from a record medium which is in the form of a card or ticket having one or more pieces or "bits" of information in a pattern corresponding to a predetermined binary or alphanumeric information. The bits of information on the record are conductive in nature and remain unaltered during the reading process.
The present invention is directed to an improvement to such a record card and to the device for reading it whereby one or more of the bits of information on the card may be "erased" or "debited" during the process of reading the card.
The record card set forth by U.S. Pat. No. 3,922,529 includes a substrate of non-conductive material on which a plurality of information bits are arranged in a predetermined pattern. These bits are formed of a conductive material and are generally rectangular in shape. The substrate is covered with a non-electrically conductive protective material which is, preferably, opaque in nature so that the information bits are not visible.
This record is adapted to be placed within a "nest" of the reading apparatus so that the surface of the record which contains the information bits faces a sensor platen which forms the floor of the nest. The sensor platen includes a conductive strip which is connected to an electrical signal source, and a plurality of individual sensing plates which are arranged alongside the conductive strip in a pattern corresponding to the pattern of the information bits on the card. Each of the sensing plates are positioned to correspond to a particular information bit so that when the record is placed on the platen the conductive information bit will serve to bridge the gap between the conductive strip and the corresponding sensing plate thereby conducting the electrical signal from the conductive strip to the corresponding sensing plate. Each of the sensing plates is connected to a detector and the detected information may be decoded to determine the pattern of information bits on the card.
The reading apparatus described above is not capable of altering any of the data on the record card. Moreover, the data on the record card is essentially permanent in nature and cannot be altered by electrical means. Thus, the device is not adapted for applications in which it is desired to "erase" or "debit" one or more bits on the record card. An example of such an application is one in which it is desired that the record card be used as a single-use ticket. Such a ticket may be used to activate, for example, a subway turnstile or a closed circuit television set in a hotel room.
An example of a presently available type of record card which contains data which may be altered is a card on which the data is magnetically recorded. A disadvantage of such a card is that the data is relatively easy to tamper with. For example, it is possible to re-record a bit which had previously been debited thereby allowing re-use of the card. A further disadvantage of such a card is its relative susceptibility to environmental factors such as stray electromagnetic radiation.